Leakages resulting from fissures, cracks, defective jointing or the like, in pipes which are laid in the ground for the supply and removal of liquids, frequently cause serious pollution and contamination problems, either in respect of the surrounding subsoil or in respect of the liquid that is being conveyed, and it is generally necessary that the pipes be brought to the surface, resulting in long and tedious road works.
Devices for the in situ restoration of inaccessible pipes by injecting a filler product are known, in particular devices which comprise one or more modules which have a cylindrical shape and a variable diameter, and are introduced into the pipe, and are then drawn along therein.
However, these devices can only restore those sections of the pipe that are situated between two manholes, the first manhole being used for the introduction of the device, and the second one for drawing it along by means of a cable or pulling chain. Furthermore, it is not possible to use these devices in pipes which have substantial shoulders or internal projections.
Other devices are known, such as the device described in French Patent 2 579 294, which are suitable only for pipes having a diameter which is sufficiently large and falls within a relatively restricted range of values. Their structural modification, with a view to extending their use to pipes of variable diameters, would be a long and tedious task, due to their complex structure.
Furthermore, as they comprise rigid elements of relatively great length, the above-mentioned two types of device cannot be used in pipes having substantial shoulders, internal projections or bends.
Finally, U.S. Pat. No. 4,429,720 describes a continuous flexible tubular body, comprising an inflatable front part and an inflatable rear part, which parts, between them, define an injection chamber for a product to repair the pipes.
The body must, however, be positioned exactly at the site where the repair is to be carried out, the site first having been identified by the injection of compressed air. The filler and a catalyst are then separately injected into the empty chamber defined by the inflatable parts and, once the repair has been carried out, the tubular body must again be withdrawn and cleaned for the following repair operation.
Moreover, in order to use the tubular body, two manholes are required and the tubular body cannot be advanced in a pipe which has internally projecting obstacles. Its rate of displacement is also very low, due to the advancement method used.
It is an object of the present invention to overcome the above-mentioned drawbacks.